This study evaluates the effectiveness and safety of PollenVax, a subcutaneous allergen immunotherapy (SCIT) drug developed for the treatment of allergic rhinitis and asthma caused by mugwort (Artemisia vulgaris) pollen. PollenVax contains a recombinant form of Art v 1 - the major mugwort pollen allergen - combined with the adjuvant Montanide ISA-51. It is the first-in-class product of this type designed for an ultra-short treatment course.

This is a randomized, double-blind, placebo-controlled Phase II study. Participants will be adults aged 18-65 years diagnosed with moderate-to-severe mugwort pollen-induced allergic rhinitis confirmed by skin prick test and/or specific IgE testing. A total of 138 participants will be randomly assigned to one of three groups: placebo, PollenVax at a cumulative dose of 22 µg of recombinant Art v 1, or PollenVax at 44 µg, administered as four weekly subcutaneous injections.

The primary efficacy outcome is the Combined Symptom and Medication Score (CSMS) during the peak mugwort pollen period (PGPP). Safety and tolerability outcomes are co-primary endpoints, assessed throughout the study. Secondary outcomes include daily symptom scores, quality of life (RQLQ/AQLQ), visual analogue scale for rhinoconjunctivitis discomfort, skin prick test reactivity, and immunological markers (Art v 1-specific IgE and IgG).

The study is conducted at a single clinical center (Medcenter-Rakhat, Almaty, Kazakhstan). Sponsor: Kazakh National Agrarian Research University (KazNARU).

Background and Rationale IgE-mediated allergic diseases affect approximately 35% of the population in industrialized countries, with prevalence continuing to rise. Mugwort (Artemisia vulgaris) pollen is among the top ten global aeroallergens responsible for seasonal allergic rhinitis and allergic asthma. In Kazakhstan, mugwort pollen is the causative allergen in 68% of children and adolescents diagnosed with allergic rhinitis and asthma. Allergen-specific immunotherapy (ASIT) remains the only disease-modifying treatment for IgE-mediated allergy, capable of inducing long-term tolerance by shifting immune responses from Th2 toward Th1 and regulatory T-cell (Treg) profiles. Conventional subcutaneous ASIT (SCIT) requires 3-5 years of treatment with frequent injections, leading to low patient compliance. There is a clear unmet need for shorter, effective SCIT regimens.

Investigational Product PollenVax is an original subcutaneous allergen immunotherapy product developed by Kazakh National Agrarian Research University (KazNARU). It consists of recombinant major mugwort pollen allergen Art v 1 combined with the oil-in-water adjuvant Montanide ISA-51 (Seppic, France). The Montanide ISA-51 adjuvant forms a depot at the injection site, enabling sustained antigen release and prolonged immune stimulation. PollenVax is the first recombinant Art v 1 product formulated with Montanide ISA-51 for subcutaneous ASIT of mugwort pollen-induced allergic disease. It is designed for an ultra-short treatment course of four weekly subcutaneous injections, with the aim of improving patient compliance and reducing the number of required clinic visits compared to conventional SCIT regimens.

Preclinical Evidence Preclinical studies in mouse and guinea pig models of mugwort pollen sensitization demonstrated that PollenVax (recombinant Art v 1 + Montanide ISA-51) produced a superior immunological profile compared to other tested formulations. Key findings included: significant reduction of total and allergen-specific IgE; marked increase in protective IgG antibodies; shift from Th2-dominant to Th1-dominant immune response; and reduction of lung eosinophilic inflammation superior to sublingual immunotherapy (SLIT)-based approaches. Efficacy was demonstrated in both pre-seasonal and co-seasonal (during active pollen exposure) administration paradigms. Safety studies in guinea pigs, mice, and rats showed no anaphylactic reactions and no delayed-type hypersensitivity responses. Acute and subchronic toxicity studies in rats classified PollenVax in Hodge-Sterner Class 5 (practically non-toxic), with the No Observed Adverse Effect Level (NOAEL) established at the maximum tested dose of 0.4 mL per injection.

Phase I Clinical Evidence A completed Phase I randomized, double-blind, placebo-controlled study enrolled 30 adults with confirmed mugwort pollen-induced allergic rhinitis. Participants received PollenVax in the ultra-short SCIT regimen of four weekly subcutaneous injections at cumulative doses of 22 µg or 44 µg recombinant Art v 1, or placebo. Primary Phase I objectives were safety and tolerability.

Safety outcomes: No deaths, serious adverse events (SAEs), anaphylaxis, or high-grade systemic allergic reactions were observed. Adverse events were predominantly mild-to-moderate local injection site reactions (redness, induration, pruritus) that were transient and self-resolving without specific treatment.

Immunological outcomes: Phase I demonstrated marked induction of Art v 1-specific IgG4, minimal IgE induction, statistically significant reduction in skin prick test reactivity, and dose-dependent Th1/regulatory T-cell immune modulation - consistent with the expected mechanism of action of effective ASIT.

These Phase I results supported the safety profile and immunological activity of PollenVax and provided the basis for proceeding to this Phase II efficacy and safety study.

Statistical Approach The primary efficacy analysis will use Analysis of Covariance (ANCOVA) with the Combined Symptom and Medication Score (CSMS) as the dependent variable, treatment group as the fixed factor, and baseline sensitization measures (Art v 1-specific IgE, SPT wheal area, ALEX² molecular allergy test result) as covariates, applied to the Intent-to-Treat/Full Analysis Set (ITT/FAS) population. A linear mixed model (LMM) will additionally adjust for potential co-sensitization to Chenopodiaceae and Ambrosia pollen as confounders. The significance level is α = 0.05 (two-sided). The sample size of 46 participants per group (138 total) provides 80% power to detect a Minimum Clinically Important Difference (MCID) of 0.33 CSMS units (assumed SD = 0.7), with a 10% dropout allowance incorporated.

Inclusion Criteria:

1. Signed and dated written informed consent prior to any study-related procedures.

2. Age 18 to 65 years (inclusive) at the time of signing informed consent.

3. Ability and willingness to comply with all protocol requirements, including attendance at all scheduled visits, completion of study procedures, and maintenance of a patient diary.

4. Clinically significant symptoms of allergic rhinitis during the mugwort pollen season, for which allergen-specific immunotherapy (ASIT) is indicated in the investigator's judgment.

5. Diagnosis of allergic rhinitis as the primary condition caused by sensitization to mugwort pollen (Artemisia vulgaris), of moderate or severe intensity, with a duration of at least 2 years, per ARIA guidelines. Comorbid mild-to-moderate well-controlled bronchial asthma (per current GINA guidelines) is permitted (ICD-10: J30.1 and/or J45.0).

6. Confirmed sensitization to Artemisia vulgaris pollen and/or its major component Art v 1, established by at least one of the following:

   • Positive skin prick test (SPT) with wheal diameter ≥3 mm compared to negative control, with adequate positive control; co-sensitization to other inhalant allergens (including ragweed) is permitted provided the mugwort reaction is the largest wheal in the tested panel and corresponds to the seasonal pattern of symptoms; AND/OR
   • Specific IgE to the above allergens by ImmunoCAP: positive result (≥Class 1), i.e., above the positivity threshold per manufacturer instructions.

7. Physical examination findings (including body temperature, blood pressure, heart rate), laboratory and instrumental parameters without clinically significant abnormalities per investigator assessment.

8. Negative urine pregnancy test at screening (for women of childbearing potential).

9. Agreement to use adequate contraception from screening until 90 days after completion of study participation (for women of childbearing potential and their partners).

10. Participants who received placebo in the Phase I PollenVax study may be enrolled if they meet all inclusion criteria of this study and had no serious adverse events related to Phase I participation.

Exclusion Criteria:

1. Prior allergen-specific immunotherapy (ASIT) to Artemisia vulgaris pollen or any other allergen within the last 3 years.

2. Sensitization and clinically significant symptoms caused by another inhalant allergen that, per medical history and investigator's clinical assessment, dominate over mugwort-related symptoms and may substantially confound efficacy assessment during the observation period.

3. Severe or uncontrolled bronchial asthma, including any of the following:

   • Forced expiratory volume in 1 second (FEV1) < 70% of predicted value at screening;
   • Clinically significant asthma symptoms despite baseline therapy;
   • Asthma exacerbation requiring systemic corticosteroids, hospitalization, or emergency care within the last 6 months.

4. History of life-threatening allergic reactions (including anaphylaxis, airway edema, bronchospasm, Stevens-Johnson syndrome, Lyell syndrome) or any allergic reaction to allergen-specific immunotherapy.

5. Chronic or acute ENT disorders at screening that may substantially affect symptom assessment or safety of study participation, including active bacterial rhinosinusitis, severe polypous rhinosinusitis, or significant anatomical nasal obstruction requiring surgical treatment.

6. Immunoglobulin therapy within 6 months prior to screening or planned during the study period.

7. Treatment with biological agents targeting the immune system (including anti-IgE antibodies such as omalizumab, other monoclonal antibodies, or immune checkpoint inhibitors) within the last 12 months prior to screening or planned during the study.

8. Immune system disorders, including autoimmune diseases and primary or secondary immunodeficiencies, except well-controlled autoimmune thyroiditis and uncomplicated type 1 diabetes mellitus.

9. Severe acute or chronic inflammatory or infectious diseases in the active phase at screening.

10. Severe, decompensated, or unstable comorbid conditions, including but not limited to:

    • Severe chronic respiratory failure;
    • Liver cirrhosis Child-Pugh class B or C;
    • Unstable angina or clinically significant ischemic heart disease;
    • Chronic heart failure NYHA class III-IV or decompensated stage;
    • Uncontrolled arterial hypertension (systolic BP ≥160 mmHg and/or diastolic BP ≥100 mmHg) despite treatment;
    • Clinically significant cardiac arrhythmias, including high-grade ventricular arrhythmias (Lown classification);
    • Myocardial infarction, acute stroke, transient ischemic attack, or pulmonary embolism within 6 months prior to Visit 0, or aortic aneurysm >6 cm;
    • Less than 3 months after coronary artery bypass grafting or coronary stenting;
    • Any other condition that, in the investigator's judgment, may affect patient safety or interpretation of study results;
    • Active malignancy of any location or malignancy within the last 5 years, except fully treated carcinoma in situ;
    • Severe renal failure;
    • Severe hepatic failure.

11. Serologically confirmed infection with HIV, hepatitis B, or hepatitis C virus.

12. Exacerbation of chronic allergic skin disease (including atopic dermatitis or generalized urticaria) at screening that may confound assessment of allergic symptoms.

13. Clinically significant abnormalities in routine laboratory tests per investigator assessment.

14. Alcohol, drug, or substance dependence within the past year per investigator assessment.

15. Pregnancy or breastfeeding.

16. Inability to discontinue beta-blocker therapy (systemic or topical) and/or presence of a condition where epinephrine use for anaphylaxis management is substantially limited per investigator's clinical assessment.

17. Use of immunosuppressive agents or other medications that cannot be discontinued during the study period and may affect patient safety or efficacy assessment.

18. Severe psychiatric or neurological disorders impairing the ability to provide informed consent or comply with protocol requirements.

19. Legal incapacity or limited legal capacity.

20. Factors indicating high risk of non-compliance with study procedures, including inability to attend regular visits, maintain a patient diary, or follow protocol requirements per investigator assessment.

Individual participant data will not be shared publicly due to confidentiality obligations under the study protocol and applicable data protection regulations of the Republic of Kazakhstan. Aggregated summary data will be available upon publication of study results.

Blinding is maintained through use of placebo identical in appearance to PollenVax (same emulsion without active substance). Study drug preparation and labeling are performed by a party independent of the clinical site. Unblinding is permitted only in medical emergencies; the procedure for emergency unblinding is described in Protocol Section 4.9.